One-Bone Forearm Reconstruction and Distal Radioulnar Joint Fusion for Emergency One-stage Operation in Traumatic Major Bone Defect of Forearm

B ackground : Major bone defects in forearm caused by severe trauma is a real challenge for orthopedic surgeons. This study aimed to evaluate the role of one-bone forearm (OBF) reconstruction combined with distal radioulnar joint fusion (DRUJF) as a rescue option under this dicult situation. Methods: In total, 18 patients with major bone defects in forearm caused by severe trauma were selected from 2003 to 2017 and followed up for 2 to 16 years. All patients were managed in the Emergency Department and received emergency one-stage OBF combined with DRUJF. In addition, patient demographics, surgical techniques, clinical outcomes and complications were collected from the medical records. Results: The mean age of patients was 41.5 years (ranging from 23 to 58 years), with 11 males and 7 females. The mean time to union was 5.8 months; 17 patients had complete union, and 1 patient had infection with nonunion requiring secondary procedures. According to the criteria of Chen, 3 patients had a grade-I functional outcome, 14 patients had a grade-II functional outcome, and 1 patient had a grade-III functional outcome. Based on the Peterson scoring system, the outcome was excellent for 3 patients, good for 13 patients, fair for 1 patient, and poor for 1 patient. Conclusion: OBF construction combined with DRUJF was an alternative surgical procedure as the emergency stage-one intervention for the treatment of traumatic major bone defects in forearm, which may be more functionally and cosmetically superior than forearm amputation.


Background
The bony structure of the forearm consists of the ulna, radius and associated articulations radius. The length of the ulna and radius is critical to the proper function of the forearm [1] [2]. Due to the unique rotation function of the forearm, the treatment of ulnar and radius fractures should be considered as an intra-articular fracture, which requires anatomic reduction to restore normal function. Despite advances in microsurgical technology, the treatment of major bone defects in forearm caused by severe trauma remains a real challenge. The key to treatment is the repair and reconstruction of soft tissues (including blood vessels, nerves, tendons, etc.) and bone tissues. To the best of our knowledge, there are no standard techniques described for reconstruction with major bone loss in the forearm [3]. Moreover, the loss of composite soft tissue and bone, scar adhesion, and repeated surgical procedures can lead to highly unpredictable functional outcome of this type of injury [4][5][6].
Under these challenging conditions, one-bone forearm (OBF) reconstruction is a feasible option that can save the limb and obtain stable and functional forearm [5][6][7][8][9]. The proximal ulna is generally xed in the distal radius in OBF reconstruction [5][6][7][8][9][10][11]. According to the description by Vitale, "the ulna constitutes the elbow, and the radius constitutes the wrist", indicating that the ulna, as the distal extension of the arm is extremely important for elbow function, and the radius, as the proximal extension of the hand, is of great importance for the function of carpal articulation [12]. There is no consensus on the indications for this operation. According to previous studies, this operation is used to treat forearm bone loss caused by congenital abnormalities, tumors and infections [5][6][7][8][9]. However, the OBF reconstruction in the radiusconstituted wrist can generally lead to longitudinal instability in the wrist, distal radioulnar joint (DRUJ) instability and chronic pain [10]. We have also showed case reports of inferior ulnar radial dislocation after OBF reconstruction ( Figure 1). Afterwards, distal radioulnar joint fusion (DRUJF) was performed as a salvage procedure. The DRUJF, similar to Sauvé-Kapandji surgery, not only enhances the stability of the wrist joint, but also attenuates the chronic pain of the wrist joints, which simultaneously has certain advantages in restoring the rotation function of the forearm [13]. Therefore, we consider whether it is possible to combine OBF reconstruction with DRUJF. To the best of our knowledge, it is the rst case report with the largest sample size of the emergency treatment using OBF reconstruction combined with DRUJF to treat major bone defects in the forearm caused by severe trauma.
In this study, to our knowledge, we introduced the emergency stage-one OBF construction combined with DRUJF with the largest sample size. We aimed to assess the role of OBF reconstruction combined with DRUJF as a rescue option under this di cult situation.

Methods
A total of 18 patients were included in our retrospective analysis from 2003 to 2017. The inclusion criteria for this study were as follows: (1) major bone defect of forearm caused by acute trauma, with intact proximal ulna and distal radius, and one-bone reconstruction can constitute stable structures (2) willingness to undergo the emergency stage-one OBF reconstruction combined with DRUJF; (3) with or without distal radioulnar joint dislocation; (4) ischemic time less than 12 hours. The exclusion criteria were as follows: (1) amputation under unstable vital signs (2) major bone defect of forearm caused by tumor, deformity, infection; (3) simple ulna or radial bone defects (4) patients with lost follow-up. The mean age of patients was 41.5 years (ranging from 23 to 58 years), with 11 males and 7 females. There were 10 cases of lesion in the right and dominant sides, and 8 cases of lesion in the left and nondominant sides. The follow-up duration ranged from 2 to 16 years. Seven out of the 18 patients presented amputation, who required replantation; and another 11 patients had severe injuries in their limbs, who required revascularization. Seven patients were injured by work-related machine (the most common type of injury) and 4 patients had road tra c accidents. This proposal was approved by our ethic committee.
The demographics of patients were shown in Table 1.

Surgical technique
All surgeries were performed by the same senior surgeon. The patient was in supine position, anesthetized with brachial plexus block, sterilized and whisked with sterile drapes in the operation area, placed with tourniquet on the upper arm, followed by debridement. Afterwards, the patient was whisked with sterile drapes in the operation area again, followed by transverse osteotomy on the ulna and radius. The length of the osteotomy is conducive to the repair of blood vessels, nerves and tendons. The hand was placed in the neutral position or pronation position not exceeding 60 °. The fracture ends were rmly xed with steel plates. Direct bone contact was used in all the 18 patients undergoing OBF reconstruction, which did not require iliac bone graft or free bula transplantation. The tendon, blood vessels, and nerves were repaired accordingly. For patients who required replantation, incision decompression was additionally performed on opisthenar to prevent ischemia-reperfusion injury ( Figure 2). Afterwards, the distal radioulnar joint was exposed, the articular cartilage cleaned was cleaned, part of cancellous bone was extracted and stuffed, 1-2 hollow nails were used to horizontally x the distal radioulnar joint, followed by postoperative plaster xation. Skin grafting or ap transplantation was further performed according to the situation of wound defect.. Clindamycin (0.6g, ivgtt, qd) was preoperatively and postoperatively used to prevent infection. Postoperative rehabilitation functional training in Rehabilitation Department included: eliminating swelling and pain, preventing joint stiffness and tendon adhesion, strengthening muscle strength, preventing muscle atrophy, etc.
Graph review and result recording Patient demographics and surgical techniques were collected from medical records. After the study protocol was approved, we conducted a prospective face-to-face follow-up investigation. The following data were collected, including: limb-length discrepancy (LLD) compared with the contralateral side, Chen Criteria of functional outcome [15] , Scoring system of Peterson [6], Functional outcome was measured by DASH scores. The mean DASH score was 12.2 points, ranging from 4.0 to 33.3 points (Table 2). According to the Chen Criteria , the functional outcomes was divided into grade I (3 cases), grade II (14 cases), and grade III (1 case). No patient had a grade IV or required secondary amputation. The mean active wrist exion was 43.9 °, the mean dorsal wrist extension was 40°, the mean forearm pronation was 43.3 °, and the active pronation was 42.5 ° ( Table 4).
The mean grip strength was 3.9 kg (1.8 to 7.5 kg) on the affected side and 34.2 kg (25 to 42 kg) on the healthy side. Seventeen patients were very satisfactory with the appearance of the forearm after reconstruction, while 1 patient was somewhat satisfactory (Table 2).
Seventeen patients can resume their physical work before injury, while 1 patient failed and could only performed daily activities. One of the 18 patients had poor e cacy. Except for partial recovery of motor and sensory functions, it was mainly due to infection at the xed site of OBF and nonunion (Table 2).
Based on the Peterson scoring system, the outcome was excellent for 3 patients, good for 13 patients, fair for 1 patient, and poor for 1 patient (  [19], and requires highly personalized therapeutic approaches. OBF reconstruction procedure has been used as a rescue option for complex forearm instability due to various causes. There is no consensus on the indications for this operation. According to previous studies, this operation is used to treat forearm bone loss caused by congenital abnormalities, tumors and infections [5][6][7][8][9].To our knowledge, the study by Peterson et al. [6] had the largest sample size among previous studies. In total, 19 patients received OBF reconstruction between 1973 and 1991 (only 1 case was caused by acute trauma, the rest cases were due to tumor resection / congenital abnormalities, etc.).
According to the Peterson scoring system designed by Peterson et al. (the Peterson scoring system is also used in our study), 37% cases were excellent, 32% cases were good, 26% cases were fair and 5% cases were poor. Allende et al. [8] reported a mean clinical score of 7.7 (the Peterson scoring system [6]), without cases of infection, nonunion or re-fracture. In our case series, except for 1 patient was somewhat satisfactory, the remaining 17 patients were subjectively satis ed with limb reconstruction, and no one was willing to accept amputation, even if the limb was short and dis gured. Based on the Peterson scoring system, the outcome was excellent for 3 patients, good for 13 patients, fair for 1 patient, and poor for 1 patient. Except for 1 patient who failed to resume their original physical work and could only performed daily activities, the rest 17 patients can resume their original physical work. Kim SY et al. [9] retrospective analysis of the clinical data of patients who underwent OBF surgery from 1994 to 2014. All patients had union with a mean follow-up of 83.6 months (range, 16-218 months). The mean pain score was 3 (range, 0-8), of which 3 were painless (score 0). The mean Quick DASH score was 39 (range, 7-75), and 4 patients had good or excellent results according to the 10-point score system used by Peterson et al. All patients were satis ed with the result. Five of 8 had complications related to soft tissues that were residual from their prior injuries and surgeries. One patient had post healing fracture requiring revision xation and 1 had a postoperative infection requiring parenteral antibiotics.Therefore, OBF reconstruction combined with DRUJF is an alternative method to preserve severe acute forearm injuries and provides therapeutic ideas.
Sauvé-Kapandji procedure refers to the DRUJF and distal ulnar segment osteotomy pseudoarthrosis to treat forearm rotation dysfunction caused by changes in the distal radioulnar joint (DRUJ). Sauvé-Kapandji procedure can relieve inferior ulnar radial arthritis or mismatch by fusing the DRUJ, resolve ulnar variability through segmental resection of the distal ulna, and restores the forearm rotation function through the formed pseudo joint [20]. Simple OBF reconstruction can generally cause wrist longitudinal instability, DRUJ instability and chronic pain [10]. Ota et al. [21] also consider that the wrist width loss after Sauvé-Kapandji procedure is associated with the aggravated carpal ulnar deviation, therefore, attention should be paid to maintaining the original wrist width to prevent progressive ulnar deviation of the wrist. OBF reconstruction was generally used alone. And we also found cases of distal radioulnar dislocation after simple OBF reconstruction ( Figure 1). We later performed DURJF as a salvage procedure. In this study, the OBF reconstruction combined with DURJF was simultaneously performed, which can theoretically maintain the line of force in the wrist for a long time, prevent the ulnar deviation and palmar subluxation of the wrist, and decrease the number of operations.
High-energy trauma can often result in comminuted long bone fractures of forearm, major bone defects, combined with skin and soft tissue defects. The upper limb defects can cause limb length differences, deformities and dysfunction, leading to therapeutic di culties in clinical practice [22]. How to effectively repair major bone defects of forearm has always been an orthopedic problem. The traditional simple bone grafting is prone to various degrees of bone resorption and infection due to a lack of blood supply and the long bone healing time [23]. Anastomotic bula segment transplantation to repair major bone defect of forearm can easily damage the posterior tibial blood vessels and the common peroneal nerve under improper operation. Meanwhile, microsurgical techniques are required, with relatively high technical requirements. In addition, a large number of muscles are attached to the bula, thus, excision of the bula segment can cause relatively great damage to the donor site; and bula transplantation could also cause knee and ankle joint instability [23]. Induced membrane technique (IMT) for major bone defects of forearm requires repeated surgeries, and second-stage bone grafting requires bone removal from the autologous sacrum, with risks of pain and infection in the bone removal area [24]. Bone extension technology for major bone defects of forearm requires the long-term wearing of external xators, with potential risks of nail channel infection and second-stage stump non-union. Yildiz et al. [25] have reported that mental problems (including anxiety, depression and paranoia) might occur in patients received external xators for over 8 months. OBF reconstruction for major bone defect of forearm can repair the composite tissue damage of forearm within one single operation, which could signi cantly shorten the therapeutic course compared with previous surgical approaches, and renders early rehabilitation training. OBF reconstruction combined with DRUJF could simultaneously improve the rotation function of the forearm, avoiding wrist joint instability. However, it has shortcomings, such as weak bearing strength. In this group of patients, the average grip strength of affected limb was 39 kg (ranging from 1.8 to 7.5 kg), and no re-fracture or internal xation fracture occurred throughout the follow-up. The most critical part of the operation is the osteotomy of ulna and radius. The length of the osteotomy should be conducive to the repair of soft tissues, especially the repair of blood vessels, nerves and tendons. Moreover, incision decompression of the forearm fascia is additionally required for cases with completely separated forearm.
There are certain limitations in this study. Although all data were prospectively collected, this study was a retrospective one. A prospective study involving a large population and long-term follow-up is required to con rm our results. In addition, a lack of a control group and statistical analysis in this study is correlated with the retrospective nature of this rare surgical procedure. The strengths of this study include a relatively homogeneous group of patients who suffered traumatic major bone loss in the forearm, and OBF reconstructions consist of the proximal ulna and the distal radius. Compared with other studies using telephone follow-up, face-to-face survey follow-up is used in our study, which avoids inconsistency between clinical results and patient evaluation as much as possible. Moreover, all the surgical procedures are performed by the same senior surgeon. Another advantage is the long-term follow-up, especially regarding the results of patient evaluations, which ranges from 2 to 16 years. To the best of our knowledge, it is the rst case report with the largest sample size of the emergency treatment using OBF reconstruction combined with DRUJF to treat major bone defects in the forearm caused by severe trauma.

Conclusion
One-bone forearm reconstruction combined with DRJF is an alternative surgical procedure as the emergency stage-one intervention for the treatment of traumatic major bone defects in forearm, which may be more functionally and cosmetically superior than forearm amputation. The study was approved by the ethics committee of Wuxi No.9 People's Hospital A liated to Soochow University. All the individuals were participating in this study with written informed consent.

Consent to publish
All the individuals were participating in this study agreed to publish the data for scienti c research.